body{margin:0;font-family:Arial;background:#f1f5f9}
.layout{display:flex;min-height:100vh}
aside{width:250px;background:#0f172a;color:white;padding:20px}
button{display:block;width:100%;padding:12px;margin:8px 0;border:0;border-radius:8px}
main{flex:1;padding:30px}
.cards{display:grid;grid-template-columns:repeat(4,1fr);gap:20px}
.card,.panel{background:white;padding:25px;border-radius:15px}